ASCA Science Highlights: Cataclysmic Variables
Follow the links to images and plotsCataclysmic Variables (CVs) are close binary systems in which a white dwarf is accreting material from a more or less normal star. Sensitive X-ray observations enable scientists to infer the detailed processes operating near the white dwarf.
- ASCA observation of HT Cas resulted in the first high quality X-ray eclipse light curve of a non-magnetic cataclysmic variable. The sharp transition indicates a compact X-ray emitting region, not much bigger than the white dwarf.
- Intermediate Polars show the spin period of the magnetic white dwarf in their X-ray light curves, for example AO Psc. In one member of the class, EX Hya, emission lines of neon, magnesium, silicon, sulpher and argon have been detected for the first time, in addition to those of iron (previously known). This is a direct evidence for the cooling of plasma as it settles down onto the white dwarf surface.
- Super-Soft Sources (SSS) are CV-like systems with continuous nuclear fusion on the white dwarf surface. The spectral resolution of the ASCA SIS has made the direct detection of absorption edges possible, which prove that they do contain white dwarfs and allow the measurement of their masses.
This page created by Dr. Koji Mukai (USRA) at the U.S. ASCA Guest Observer Facility.
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